Inserting New Object Into Specific Array Index

Question

There is a MongoDB collection, which is an array of objects being returned from an Angular Resource.

[{_id: "565ee3582b8981f015494cef", button: "", reference: "", text: "", title: "", …}, 
 {_id: "565ee3582b8981f015494cf0", button: "", reference: "", text: "", title: "", …}]

I have to allow the user to insert an object into any index of the array, and save to MongoDB through Mongoose.

var object = {
    button: "",
    image: {},
    reference: "",
    text: "",
    title: "",
};

I understand how to push the object to the end of the array, but how can I specify what index for the insertion?

So far, thinking of first creating the object:

Slide.create(object, function(result) {
    console.log(result);
});

Then using an update method to update the position in the array:

Sede · Accepted Answer · 2015-12-02 13:44:55Z

Suppose you have the following document in your collection

{
        "_id" : ObjectId("565eed81abab97411fbe32fc"),
        "docs" : [
                {
                        "_id" : "565ee3582b8981f015494cef",
                        "button" : "",
                        "reference" : "",
                        "text" : "",
                        "title" : ""
                },
                {
                        "_id" : "565ee3582b8981f015494cf0",
                        "button" : "",
                        "reference" : "",
                        "text" : "",
                        "title" : ""
                }
        ]
}

You need to use $position operator to specify the location in the array at which the $push operator insert elements and as mentioned in the documentation:

To use the $position modifier, it must appear with the $each modifier.

Demo

var object = {
    button: "",
    image: {},
    reference: "",
    text: "",
    title: "",
};

db.slide.update({/*filter*/}, 
    { '$push': { 'docs': { '$each': [object], '$position': 1 } }
})

You newly updated document will look like this:

{
        "_id" : ObjectId("565eed81abab97411fbe32fc"),
        "docs" : [
                {
                        "_id" : "565ee3582b8981f015494cef",
                        "button" : "",
                        "reference" : "",
                        "text" : "",
                        "title" : ""
                },
                {
                        "button" : "",
                        "image" : {

                        },
                        "reference" : "",
                        "text" : "",
                        "title" : ""
                },
                {
                        "_id" : "565ee3582b8981f015494cf0",
                        "button" : "",
                        "reference" : "",
                        "text" : "",
                        "title" : ""
                }
        ]
}

void · Accepted Answer · 2015-12-02 12:38:05Z

0

var object = {
    button: "",
    image: {},
    reference: "",
    text: "",
    title: "",
};

arr.splice(2, 0, object);

Will push the object in the array at 2nd index i.e. it will be the third element.

answered Dec 2, 2015 at 12:38

void

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1 Comment

John Spiteri Over a year ago

I need to update this object to MongoDB... will clarify question. TY

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